Osteochondral autologous transfer surgery (OATS) or mosaicplasty is performed for small-medium size cartilage defect in the knee. This is performed arthroscopically, where your surgeon will first assess the defect, then harvest piece of cartilage with the bone plug from a less load bearing part of the patient’s knee and transfer it to the defect. The bone plug is expected to heal in 2-3 months and provide normal cartilage cover in the affected area. You will be allowed protected weight bearing initially after the procedure along with physical therapy.